Radiology is a medical specialty that uses imaging to diagnose and treat disease seen within the body. Radiologists use a variety of imaging techniques such as X-ray radiography, ultrasound, computed tomography (CT), nuclear medicine, positron emission tomography (PET) and magnetic resonance imaging (MRI) to diagnose or treat diseases. The acquisition of medical imaging is usually carried out by the radiographer. Radiologist then interprets or "reads" the images and produces a report of findings. Report is then transmitted to the physician who ordered the imaging.